Method and apparatus for separating ore particles



Dec. 8 1925. 1,5 6'4,73I

J. WEATHERBY;

' METHOD AND APPARATUS FOR SEPARATI IiG ORE PARTICJJES Fil ed July 21.1922 4 Sheets-Sheet '1 i Elma wow Q 1 s5 f 5 Dec. 8,1925- J. 'WEATHERBY-METHODAND APPARATUS FOR SEPARATING' ORE PARTICLES Filed July 21-,

1 922 4 Sheec s-Sheet 2 ,J. WEATHERBY METHOD AND APPARATUS FORSEYARATING 03E PARTICLES Filed July '21, 1922 4 SheetS -Sheet' s J,W'EATHERBY Dec. 3"

METHOD AND APPARATUS FOR'SEPARATING ORE PARTICLES Filed July 21, 1922 4Sheets-Sheet 4 JOSEPH EATHERBY, OF NEW CUMBERLAND, PENNSYLVANIA,ASSIGNOR, BY DIREGT AND IIIESHE ASSIGNMENTS, T WEATHERBY ORE, SEPARATORCGMPANY, OF HILADEL?HIA, PENNSYLVANIA, A CDRYORATION 0F DELA'WARE.

laIETHQD AND A'PIEAEATUS FOR SEIQARATING ORE PARTIICLEE.

Application filed July 21, 1922. Serial No. 576,622.,

To all whom may concern:

lie it known that l, Josnrn ii' m'rnnsnr, a citizen of thc UnitedStates, residing at :len' (Run crland, in the county of Cranberlandflllkl atc of Pennsylvania, have in vcntc l certain new and usefulimprovei'nents in iiiethods and Apparatus for Separating Ore Particles;and I do hereby dcclarc n": :hwllowing to be a full, clear, and mar-tr!i 'fiion oi lhc same, reference being had to the accompanying drawings,

"forming part oi this 51' ccification.

lily invention relates to an improved method of scparnting ore particlesfrom thcii .1 pie, and one ore from anot icr, de their susceptibility toalternatmagnetic flux and their porcrrneable qualities.

a ration ore particles from their l of one particular ore from an- I theuse of niulli-phase alternating filllfil); in the type of magneticseparator shown in drawings attached and described in the foil; ngspecification.

l have and that by passing an alternal- 1m: ic flu): tl'irough mostinineralsand metals, a countcrclcctro-nioliive force is set up withinsuch minerals and metals rc- ;'J' il out uc.wiingly (iJJPGIlCli-Bllt onohmic resistan c what .i Will. tcrin responsive] lfreqi icnc and MT) apower factor of the minor; at certain frequencies.

lror insi n :u :1 piece of iron is attracted current magnetic pole and lfrequ ncy;whi a cd away fr the -a-lcctrornotivc force 7 d in accordancewith i Elcctromagnetically in duced Curr nts always have such adirection lhat'the action. of the nmgnetic fields set up them 1:. .os tostop the motion which produces them, A further form of IJQDZ S law isthat jill lndllcfil'l current is always in such a dirtcl'" change in llWhy copycaare repelled x plaining meld, While invention more particlarly relalcs,

of their magnetic pcrmeabililiy,

that its field opposes any ,lU metals iron due to its magneticpermeability is at tractcd.

I have further found that all magnetic -pcrmcabls suhstanccs such aswould be attractcd by a hand magnet, respond to an aliQl'DlIilllfZcurrent magnet with a varying degree of speed dependent on theirreluctance and the frequency used i. e., if three or more magneticsubstances be mixed to- ;gcther, such as ore particles from differentlocalities, iron filings, etc all will jump and strongly adhere to ahand magnet and they all appear to be equally attracted, but if thesesame particles are subjected to an alternating magnetic field, they willnot all respond alike to the magnetic attraction for while one respondquickly to a certain particle will best respond. Particles of a highmagnetic permeability respond to an alternating field much more fecblythan those of low permeability, and this must be borne in mind, to avoidconfusion between magnetic permeable ores and nonmagnetic metallicsubstances in the following specification. 1

Sonie magnetic ore particles will respond freely to cycles and fecbly tocycles alternating current field While a piece of copper or aluininunrorother nonmagnetic metal which is of minus permeability will be repelledviolently, seemingly dependent upon their ohmic resistance or capacityand not upon their niagnetioqualities.

A magnetic ore particle having. an alternating current magnetic fiuxipassing through it"will respond with a counterflux either in 1 e withthe current that energizes it, or iagging behindthc current at that oreparticle. The ore particle will be Filfiuenced by several quick orsluggish dependent upon the fremoney that energizes it and ii itsresponsive frequency is lower than the frequency that energizes it thenit will lag to the alternating magnetic attraction.

If an ore particles res onsive frequency is faster than that of anot erore particle it can be separated from such other ore particle by thefact of it responding to' magnetic attraction away from the reluctantparticle. If one ore particle has magnetic permeability and another onehas minus magnetic permeability but is metallic, then the one particleis attracted and the other one is repelled, and both can be separatedfrom a gangue material which is neutral to electrical or magneticaction.

I have now described the actiizu' minerals and metals influenced by antiielllating magnetic flux, and will now describe them and their actionwhen they are in alternating currents spaced apart, but acting as awhole, and known to the art as multi-phase alternating; currents.

Reference will be made to the attached drawings which describe thepositions of currents and magnetism at various instances, together withmechanical devices to take advantage of the phenomena for the usefulpurpose of separating minerals one from the other as will hereinafter beclearly described.

Three phase alternating current is used to describe this case as it ismost convenient for this purpose, but it is to be understood that anymulti phase current answers equally well when suitable electricalconnections and arrangements are provided.

Figure l is a sine Wave diagram of three phase alternating current.

Fig. 2 is a diagram combining the three phases to form one magnetizingcurrent.

Fig. 3 shows the diamond shaped overlapping coils of the field magnetswhere one side of the coil is in the top of one slot of the fieldmagnet, and the other side of the coil in the bottom of a further slotto form north and south poles, and also showing the electricalconnections suitable for three phase a1ternatingcurrent.

Fig. d shows a section of an armature with its single pole wound coilsand elem trical connectiona Fig. 5 is a cross section through the coreand coils of Fig. 3 with one side of each coil in the bottom of one slotand the other side in the top of a following slot, also showinginstantaneous values of the magnetic field.

6 is a side elevation of. the septa Fig. 7 is a central verticalelevation 01 RAG alternating current magnetic feed hopper. Fig. 8 is ai'ra mentary view oii the feed hopper looking down at the magnets thatwearer ,A multi-phase current is a rotating or a progressing current,that is, one current follows another spaced a definite distance apart,as for instance as shown 111 Fig. 1

which illustrates a sine wave three phase alternating current where eachof the three alternating currents, a, b and a differ in phase by onethird of a cycle or 120 electrical degrees. lBy reversing the directionof the current. in the coils of one phase, .7) for example, from thedirection or that in the other two phases these three currents arecombined to form one magnetizing current and a rotating magnetic fieldsuch as that shown in curve (Z of Fig. 2 will result.

10 is a field magnet built of thin sheets of iron bolted together andarranged with teeth and slots as shown, and A, B and {l are properlyconnected coils placed on the teeth or in the slots as shown in Figs. 3and l, the electrical connections to the coils being so arranged thatthe first coil A is nected to a phase lead, the second coil B isconnected to I; phase lead and the third coil C to 0 phase lead forminga rotating or progressing magnetic field. Permeable ore particles areattracted to the poles or teeth and are caused to progress with therotati field to a discharge by no other mechanical means than therapidly moving magnetic field, while minus permeable metallic particlesare repelled from the advancing field.

This can best be described by referring to Fig. 5 which shows a crosssection cut through the core and coils of field magnet, Fig. 3, with oneside of each coil in bottom of slots 11,12 and 13, an'dlnarlred A, B,and C, and their other sides in the top oi? slots l4, l5 and 16, andmarked A, B, and. C, respectively. By means of Fig 2 and Fig. 5 takentogether it is possible to build up small pictures the magnetic heldfrom instant to instant and show how it moves in the core and air gap.

These small pictures, of which one is shown in Fig. 5, can very well hemom pared to the individual small pictures or". a moving picture him asthey appear Wh A re film is at rest, and the rotating magnetic [ielcl asit really exists could be compared to the same film when in motion andthrown on the screen.

A current is ics ier;

ire

' ferent positions.

iceavsx +0.5 since they are half their maximum value and are also abovethe reference line XX.. Similarly, the titre represented by the verticalline 2 winch is called position 2 in 2 the values oi? a and h are +0666and the 0 curve at zero. The value 0.866 is obtained because the currentcurves ai'call What known as sine curves and the reference points orpositions 1, 2, 3,

etc. are taken of a complete cycle apart. A complete cycle is 360 el: ticul degrees similar to the degrees of a circle, and hence the referencepositions l, 2, 3, etc, are of 36!) degrees or 30 degrees apart.

From a table of natural sines, it will be found that the sine of 30:O.5,sine of :O.8*36, sine of :1, sine of 0.866, sine of :(L5, sine ofContinuing from 180 toBSO the same values recur with (1 except that theyhave a minus sign since they are measured below the horizontal referenceline. It these values which are used in plotting thepictures in Fig. 5and the values for the dif- Starting from any arbitrary point as at a:Fig, 5, position 1, the line moves in direction and. amoun according tothe value of the current in slotli. Slot 11 contains the coil and thevalue of the current is +0.5 is shown. by the vertical line positionone, in Diagram 2 since thedirection of the plus up, the line is drawnupward. from a; to e and cf is drawn horizontally representmg by itsheight aboverc the current in'slot 11, and the magnetic field at thatpoint. From 7' the line goes up to 9 making fg twice as long as debecause the B coil is in slot 12 and the value of the current in'B coilis +1, or twice that in A, and the line h is drawn horizontally,representing by its height above as the current in slot 11 plus slot 12and therefore the magnetic field at that point. From h the line goes upto 2' because the G coil is in slot 13 and the current in the (E coil asshown at that instant is +0.5. The line if is drawnhorizontally-representing its height above 02 the combined mirrcnts in.slots .11 plus slot 12 plus; slot l3 and therefore the magnetic field atthat point.

From j the line drops down to because the A conductor in slot 14 and theA conductor is the other side of the A coil and hence the current in. itis in. the opposite direction of that of the A side. If the current inthe A side was considered +0.5, the current in the A side must be +0.5and, hence the curve drops down for a minus value from j to k. Similarlyit drops twice as far from Z to equals +1 and I therefore the other sideof ll (501i or B must equal -l. -l ollowing the curve in this manner ton and 0, it completes one cycle of one north and south pole. The

m since B- l. by the vertical arrow not have such sharp curves but wouldbe" smoothed out into practically a sine curve such as the current inFig. 2, but lor the purpose of illustrating the rotating licld thecurves are to he considered square shouldered as shown.

Seven positions of the three areshown in Fig. 5 and it will be. notedthat the center of the north and corresponding south poles have traveledthree slots to the I left which in this case means 189 electricaldegrees. 7 lt Will now be seen that it a magnetic permeable substance beintroduced into the, rotating magnetic field,

influence of this the substance will be attracted to the'teeth or polesand will then advance or with, and in the direction olvthe progrcs:

ing or rotating magnetic field at a speed dependent on the frequency ofthe electr c current energizing the magnetic field.

f a non-magnetic, stance, such as copper, silver, zinc, etc. be

electric currents will be induced into them by the action of thealternating magneticflux, and according to Lenzs la Since the magnet isa fixed ho ly but the currents Within are moving the magnetic acted uponare free to move. pelled away from the teeth ing magnetic field at aspeed dependent on the frequency of the magnetic current.

Types of separators suitable substances from a gangue material, fromanother by the ternatmg currents-f wlllunow be described,

I S v 1 l with a i'urthcr description of the ores and 7 connection :with

method of treatment -,in such separators.

Reference will now be had On the inner sides of the frame 20 are brackets ill on which rests to Fi a brackets. Suspended rigidly blocked gtoit by U-bo'lts 23 and comprising. a part of it, is a field ma securelyto form aud radiation of heat and are more clearly shown in Figs. 7 anddercd as that part abovel l. The center of the tor of the south pole,pointing down... In

phase current progressy but a metallic sub-, ,1 aluminum 9. introducedinto the influence of this alternating rotating magnetic field,

to the scpara-H tion of magnetic or non-magnetic metallic or one use oi?multiphase ali l shaft 22 'which gis free to turn on I from the shaftbut y is a frame work 2% vl Vith n the frumcfwork, -lie net 25 which iscomposed 01 many sheet are s urred apart to l ture and the field magnet.

8. The units are all bolted .to ether to form a single field magnet. Theold magnet 25.ha-s many teeth that form poles 27 and slots 28 toacconnnodate the windings or coils. For the sake of clearness thewindings are not shown in Fig.- (3, but are shown in Figs. 3, 4 andAdjustably spaced below field magnet 25 and resting in the frame 20 onadjusting bolts 29 is an armature 30. The armature is a duplicate inconstruction of field magnet 25 with the exception as to length, itbeing shorter to permit the free discharge of ore concentrates. Acrossthe base 31 of armature 30 and securely bolted to it is an angle bar32.Holes are bored in angle 32 to accommodate the adjusting bolt 33 to slipthrough up to its head. At its other end 34 bolt 33 is threaded andpasses through frame work 2% and is so arranged that by turningadjusting nut 36 the armature will slip forward or backward in the frameparallel with field magnet 25 permitting the proper adjustment withmagnetic relation between the teeth or poles of the arma- By turningadjusting bolts 29 the armature 50 1nay be adjusted closer to or fartherfrom field magnet 25, thus changing. the air gap between them.

Adjustably hung below the field magnet 25 and supported from the frame24: by adjusting hanger bolts 37 is a board l0 composed of a nonmagnetic andnon-metallic substance such as glass, wood or any suitableinsulating composition. This board has two functions, one to keep theore concentrate a proper distance from the pole teeth in the. air gap,and second to provide a surface on the under side of which the oreconcentrate follows the rotating magnetic field to a point ofconcentrate discharge.

Attached to the lower end of board to is a wedge shaped section all orthe board can be bent or shaped at its lower end to conform. When theore concentrate arrives at this section in its progression with therotating magnetic field, it is forced to move farther away from the poleteeth and as the current at this section is weakened, the ore willfreely drop away from the field to its discharge, being guided by theadjustableplatfonm 42.

Directly above armature 30 and adjustably hung from the frame' 24 byadjustable hanger bolts 3'7 is an ore feed distributing board 45. Thefunctions of this board are to receive the ore to be treated orseparated at its top, supporting the gangue material as it slides bygravity to its bottom discharge and supporting the ore at its properdistance between the field and armature in the air gap. This board' canbe independently adjusted toward or further away from the armature orfield. The armature can also be independently adjusted toward or furtheraway from the feed board by adjusting bolts 29. Fastened to the upperpart of magnet frame 2i is an adjusting bolt 46 having an eye 4:? at oneend through which a bolt 48 passesthat holds it to frame 24 in such a.way that it is free to turn, while the other end is threaded, and has anut 49 and washer 50 This bolt passes through a hole in the projection51 on frame 20 and is arranged so that by screwing the nut in onedirection or the other the magnet frame 24 together with its enclosedmembers can be tilted on an angle to permit the free flow of ore bygravity down and over the feed board 45.

-M'ounted within the frame 20 at its top is an alternating currentmagnetic hopper 50 best shown. in Figs. 7, 8 and 9. The hopper is soarranged that it will discharge its granular ore feed to the top of feedboard 40. The hopper is actuated in such a way to prevent fine ores orgranular materials from packing or arching, and permits an accurate andgranular feed to, pass under its gates even under severe conditlons suchas moisture in the feeding materials that tend to agglomerate and stickthe feed materials in lumps, balls, etc. The ore or other feed materialrests on the angular base 52 of the hopper box as shown- On each sideand projecting from the lower part of the hopper are angle bars 53 whichare reinforcement for the sides and support the bottom and the followingmechanism.'

In the bottom of the hopper is an iron plate 55 which acts as a liningand in turn projects over a vibrating spring 1 steel diaphragm 56. Thisdia hragm rests on and is fastened to corner. locks 57 in such a waythat it is free to vibrate, and the blocks in turn are rigidly fastenedto the inner legs of angles 58. Adjustable but securely hung from anglebars 53 by threaded stud bolts 58 is an alternating cur rent magnet ($0composed of laminated iron punchings forming poles for the coils whichenergizes it. The coils can have either single phase or multi-phasealternating current to energize them, but as it is always possible touse single phase from a multiphase circuit, single phase is preferred.The alternating current magnet is directly under the diaphragm and isadjustable to or away from it by the nuts 59 on the stud bolts 58.switched on the windings or coils the diaphragm is attracted to themagnet and released from it by the action of the alternating currentchanging from positive to negatlve and violently vibrates it accordinghen the alternating current is to the frequency'of the current thatenerf gizcs the magnet. When the magnet (30 is. adjusted toward. or awayfrom the l kir- .rial, thus preventing diaphragm 56 the vibrations arestronger opper. On thcpart inside, the orcor other feedrests upon thediaphragm while'the outside section guides the feed to the dis charge.The action is as follows: The hopper is filled with the granular ore orother material to, be fed which rests partly on the bottom plate and thediaphragm 56. The gate 62 is raised to permit a sufii cient'feed to passunder, between it and the diaphragm 56 and sidewalls. The current isswitched on and the diaphragm violently' vibrates.

This vibration not only passes through the material resting 'on thediaphragin but also to the surrounding matepacking and arching, and atthe gate itself.- The material no matter how finely ground will beviolently agitated and will pass under the gate whether in a thingranular ribbon or in a thick stream. Afterpassing'thc gatethe dischargeis still kept in granular shape and in motion by the outward extendingportion of the diaphragm 56.

' The field magnet alone may be used as a separator, and may be placedabove or below an ore feed board, or by proper electrical connectionsthe armature andfield'can be considered as one certain poles in thefield, fer-instance, every other one, will be field poles for likeadjacent poles in the armatureand the follow mg poles be armature polesto like field f poles in the armature. That is, the susceptible oreparticles following the rotating field will first jump up to a fieldmagnet tooth or pole and then down to the next armature tooth or pole,which is changed to a field tooth or pole, and then up, and so on to adischarge as would be the case in Fig. 6 if single pole coils were 'usedas shown in section in Fig. 4, the first tooth" in the field magnethaving an A coil, the

second toothih the armature having. a B coil, the third tooth inthefield having a C coil. the fourth tooth in the armature havingan A coil,etc, all the coils being properly connected together in proper phase re-.lation while the coils on the teeth between can have their coils shortcircuited, thus forming armature teeth or poles for either section. Theobject of the armature is merely to intensify or concentrate themagnetic field to improve the power factor and further to increase thedistance in which ore is susceptible to the field influence.

, that can be used substances as they and arranged so that alternatesback and forth across the air the armature The field magnet 25 has coilsand is connected as shown in section Fig. 3, while the armature 30 hassingle pole coils and is are connected three" can be used on eitherarmature or field to meet different conditions in' the ore to beseparated, as each type'has peculiar features advantageously in variousways.

In the following description I describe the diamond overlapping coil onthe field";

and the single pole COIlOll the armature, this being the preferableconstruction. Now

consider that ath'ree phase alternating cur-' rent has been switched onthe field magnet and 'currentiis flowing in all the'coils A, B and C,etc. An adjustable resistance or an coils of the-field'magnet to tapertheir imagnetic impedance is used on the lastfew strength in such a waythat each following tooth or pole is weaker in magnetic strength 9 isdone to perthan the one before it. This mit magnetic susceptible oreparticles to be released and sary in the i to drop away from the rotatQ111g o1- rogressing field. This is not' neces caseof non-magneticmetallic are repelled by'and away from the rotatingfield, while themagnetic i substances are attracted to and advancefwith the rotatingfield.

No provisions have as the connection of the terminal wires leading romthe armature poles of the. armature have their terminals short-'cir-'cuited or closed. Current is now flowing in all the teeth OIf'pOleS' areenergized witha rotatln magnetic field all the field coils and D fordiagrams Fig. 5.

as was-described Magnetic fiux is now flowing through the field. magnetout the tips of the poles or teeth and across the teeth through thearmature, back through the teeth and. air gap to the field poles onteeth again. This sets up a strong magnetic" field in the armature teethby induction" of the field,

which rotates in step with that magnetism that energizes alternating,

it. The current is therefore the magnetic flux p at a speed equal to thefrequency and the poles or'teet reverse their polarity chang.

ing from north to south and back to north again very rapidly, as forinstance in 60,

yet been made for with the exception that the coils on the last threeteeth or air gap to the armature 10f both the field magnet and cyclecurrent they would change polarity 7200 times per minute.

When the coils on the armature are open eircuited no current flowsthrough them. The armature iron is magnetized by the field flux flowingthrough it. Magnetic permeable particles have a tendency to bridgebetween the armature poles and the field poles, even though they arespinning in step with the frequency.

When the armature coils are closed circuited as shown inthe last threecoils of Fig. 4., current flows in them causing a counterfiux to be setup in the armature which opposes the field flux that energizes it, thuscausing the permeable ore particles to be repelled. in the direction ofthe field poles as they travel with'the rotating field.

Since non-magnetic metallic substances are repelled away from themagnetic field in any case, it makes little difference whether thearmature coils are open or closed tor non-magnetic metallic substances.By 1ntermittently opening and closing the arma ture coils permeable oreparticles are caused to jumpup and down violently during theirprogression, as well as to spin thus free ng themselves from the ganguematerial which tends to adhere to them.

It will now be considered that all the armature coils are closedcircuited and thatv the field magnets are tilted to such an angle thatore will freely flow down the feeder board in the air gap between thefield and armature, to a discharge.

It is to be noted that there are nomoving parts on this type ofseparator and that all ore moves by gravity alone or is forced to travelwith or againstgravity by the rotating magnetic field.

The gate of the hopper is now opened and a granular stream of orepermitted to flow to the feeder board 45. v The gangue material which isnon-metallic and is not affected by the alternating current flux, flowsdown the feeder board to its discharge at the bottom.

The permeable magnetic particles on em tering the field even though theyare as fine as dust, have natural polarity and will start to spinrapidly when the alternating flux passes through them trying to presenttheir Cir l poles in proper relation to the lines of force, I thusfreeing themselves from gangue material, and one from the other. Theyare also repelled from the armature poles and in the direction of thefield poles and they are influenced to" travel with the rotatingmagnetic field. They travel down on the I under side of spacer board 40at great speed.

much faster than'the gangue that is flowing by gravity on the feederboard 4.5. l/Vhen they reach the bottom of the spacer board it) they areforced away from it by the wearer to the magnetic material travelingwith the.

rotating field. In such a case-itis arranged that the armature coils beintermittently opened and closed, which causes the ore particles toviolently jump up and down between armature and field as Well as spinwhile they are traveling to their discharge with the rotating fieldcurrents, as the armature is first attractive when the coils are openedand then repellant when the coils are closed.

What I claim is:

1. The art of electrically separating magnetically permeable particlesfrom gangue which consists in passing a mixture of particles and ganguebetween a progressive guillti-phase magnetic field and an induced 2. Theart of electrically separating magnetically permeable particles fromgangue which consists in passing a mixture of particles and ganguebetween two progressive multi-phase fields.

3. The art of electrically separating magnetically permeable particlesfrom gangue which consists in passing a mixture ofparticles and ganguebetween two progressive multi-phase fields,-the current in one of saidfields being induced by-the current in the otherfield.

4:. The art of separating magnetic particles from gangue which consistsin passing the mixture of particles and gangue across a multi-phaseprogressive field which moves with the path. of the mixture, inincreasing the frequency of said field until maximum movement of theparticles is secured, and in continuing the current in the field at saidmaximum responsive frequency.

5..The art of separating non-magnetic metallic substances from magneticsubstances and from gangue which consists in passing the mixture over arelatively thin inclined non-magnetic surface under which is-placed anelectromagnet excited by a multi-phase alternating current so that therotating or progressive field moves with the passage of the mixture downsaid inclined surface.

6. The art of separating magnetic ore particles from gangue whichconsists in passing a mixture of gangue and particles between amulti-pole electromagnet and an armature, said magnet having amulti-phase progressive magnetic field moving parallel particles andgang'ue through the margin only of a progressive field moving in the adirection of material flow.

9. The art of electrically separating magnetically permeable particlesfrom gangue which consists in passing the mixture of particles andgangue through the curved portions only of the lines of force of aprogressive field moving in the direction of material-flow. v

10. The art of electrically separating magnetically permeable particlesfrom gangue which consists in passing the mixture of particles andgangue between two progressive fields moving in the direction of theflow of the material while restraining said mixture from crossing thestraight and nearly straight portions of the lines of force of each oisaid fields;

11. The art of electrically separating magnetically permeable particlesfrom gangue which consists in passing the mixture of particles andgangue between two insulating surfaces, each spaced from a progressivefield whereby the mixture is constrained to move in the region ofthecurved lines of force of each field.

12. The art of electrically separating magnetically permeable particlesfrom gangue which consists in passing the mixture of particles andgangue along. a nonmetallic surface spacedfrom a progressive fieldwhereby the mixture is caused to move in the margin only of said field.

13. In a separator, an electro-magnetcore having parallel teeth,windings for said teeth, multi-phase alternating current for energizingsaid, coils to produce a moving magnetic field, and a non-magnetic platebelow the toothed pole faces and providing a guiding surface for thematerial being separated.

14. The device of claim 13, characterized by the plate being adjustabletoward andaway from the magnet.

15. The device of claim 13v in combination with an armature for themagnet. I

JOSEPH WEATHERBY.

